Appendix I. Acronyms and Terms

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Home Antarctic MeteoritesLunar Meteorite CompendiumAppendix I. Acronyms and Terms

Lunar Meteorite Compendium
Appendix I: Acronyms and Terms

growth of solid bodies through collisional aggregation of smaller bodies.
meteorites that lack chondrules (stony and iron meteorites).
melted material (glassy) found in lunar regolith
Alkali suite
rock suite identified in the Apollo samples consisting of relatively high Na and K contents (and more ferroan)
Antarctic Meteorite Newsletter (issued by NASA JSC, Astromaterials Curation)
achondritic meteorites consisting of dipopside-rich pyroxene, olivine and plagioclase, with a roughly basaltic composition.
angular momentum
a property of rotating systems that depends upon mass and its distribution, angular velocity, and radius. The angular momentum of the Earth- Moon system is contained in the Earth's rotation and the Moon's orbital motion.
the calcium - rich end member of the plagioclase feldspar mineral series; CaAl2Si2O8
an igneous rock made of >90% plagioclase feldspar.
Antarctic Search for Meteorites, funded by U. S. National Science Foundation; led by William Cassidy and Ralph Harvey.
NASA manned missions to the Moon in 1969-1972, which returned rock samples to Earth (at NASA Johnson Space Center)
Astromaterials Research and Exploration Science at the Johnson Space Center
the mean distance between the Earth and Sun (1.496 × 1013 cm).
a fine-grained, dark colored igneous rock comprised primarily of pyroxene, olivine, feldspar and glass.
"blue ice"
Locations in Antarctica where samples were recovered (appendix IV) ALHA
Allan Hills region of Antarctica Asuka - Asuka Mountains EETA - Elephant Moraine MAC - Macalpine Hills MET - Meteorite Hills MIL - Miller Range PCA - Pecora Escarpment QUE - Queen Alexandra Range Yamato - Yamato Mountains
British Museum of Natural History, now The Natural History Museum, London.
a rock comprised of coarse, angular mineral or rock fragments embedded with a fine-grained matrix
bulk silicate Earth
see " primitive upper mantle"
event proposed for the Moon and inner solar system whereby a heavy flux of material caused a heavy bombardment of impactors at about 3.9 Ga
chalcophile element
an element with a preference for sulfide minerals
Chinese Antarctica Research Expeditions
the most abundant class of stony meteorites that contain chondrules
rock fragment found within another rock such as in a breccia
mission to the Moon providing elemental maps and other data
mineral of the pyroxene group such as diopside (CaMgSi2O6) or pigeonite ((Ca,Mg,Fe)2Si2O6).
compatible element
a minor or trace element which partitions readily into crystalline rather than melt phases.
young crater on the near side of the Moon
dense, metal- or sulfide-rich central region of a planet.
cosmogenic isotopes
Isotopes produced by interaction of high-energy cosmic-rays with elements in sample.
large basin on the near side of the Moon
outer, highly differentiated region of a planet.
a plutonic igneous rock composed chiefly of crystals accumulated by sinking or floating in a magma.
Dar al Gani, Libya, where many meteorites have been found
wind erosion area
Dhofar, Oman, where many meteorites have been found
the process by which planetary bodies develop concentric zones that differ in chemical and mineralogical composition.
achondrite meteorite comprised of orthopyroxene and minor amounts of olivine and chromite.
a peridotite comprised of >90% olivine, with accessory pyroxene, chromite or plagioclase.
disintegrations per minute educational
thin section set
JSC, BM(NH) and NIPR all have sets of thin sections of meteorites, with educational pamphlets, for use by educational institutions.
ejection age
the sum of the exposure age and terrestrial age, the time since the sample was ejected from the Moon
electron microprobe analysis
escape velocity
the speed an object must attain to escape from the gravitational field of another object.
a basaltic meteorite composed essentially of feldspar and clinopyroxene
exposure age
The time interval a small body (~1m) spends in space as measured by radionuclides generated by high energy cosmic rays.
extinct isotope
a radioactive isotope that existed when the solar system formed, but with too short of a half-life to allow detectable amounts to remain now.
ferroan anorthosite - ancient anorthosites found among the Apollo and lunar meteorite suites
a group of aluminous silicate minerals, with K-, Na- and Ca-bearing end members.
Feldspathic highlands terrane (FHT)
large terrane on the Moon made primarily of feldspar-rich material
Ferroan anorthosite (FAN)
ancient anorthosites found among the Apollo and lunar meteorite suites
the separation of chemical elements from an initially homogeneous state into different phases or systems.
fractional crystallization
formation and separation of mineral phases of varying composition during crystallization of a silicate melt or magma, resulting in continuous change of composition of the magma.
a thermodynamic function used instead of pressure in describing the behavior of non-ideal gases.
fusion crust
thin glass coating found on outer surface of meteorite due to heating by atmospheric entry
gram (also Kg = kilogram and mg = milligram etc.)
1,000,000,000 years
Giga Pascals (unit of pressure)
a coarse-grained, dark igneous rock made up chiefly of plagioclase (usually labradorite) and pyroxene. A coarse-grained equivalent to a basalt.
a group of minerals with the general formula X3Y2(SiO4)3, in which X = Ca, Mg, Mn or Fe2+, and Y = Al, Fe3+, and Cr3+.
genealogy diagram
Diagram that shows the relationship of rock splitting and allocations. The number before the comma is called the generic sample and the number after the comma is the " daughter" split.
giant impact theory
the theory that the Moon formed from material ejected into Earth orbit during an impact between a large impactor and the proto-Earth.
gravitational instability
condition in which slight rearrangements or concentrations of a relatively uniform distribution of mass can, by their gravitational effect, initiate substantial further contraction of mass into even more localized concentrations.
gamma ray spectroscopy
Howardite, Eucrite, Diogenite. Large group of achondrites, related by mineralogy and petrology - howardites are brecciated mixtures of eucrites (basalt) and diogenites (opx).
High titanium basalt
class of lunar basalts with very high Ti content, compared to other lunar basalts (and especially compared to terrestrial basalt)
Highly siderophile element (HSE)
see noble metals. Also, defined by having metal/silicate partition coefficients at 1 bar > 10,000
a type of basaltic achondrite that is brecciated.
an index for maturity of lunar soils; the ratio of Measurement of Single- Domain, Nanophase Fe0 (IS) to FeO
inductively coupled plasma mass spectrometry
isotope dilution mass spectroscopy
instrumental neutron activation analysis
an oxide mineral with the composition FeTiO3
large basin on the near side of the Moon
impact melt
melted rock that forms during impact of one body with another (common on the Moon)
impact parameter
A term relating to the geometry of a collision between two spheres; it is the offset between the spheres' centers projected perpendicular to the line of approach.
the angle between the plane of a planet's orbit and the ecliptic (Earth's orbital plane), or a satellites orbit and its planet's equator.
incompatible element
a minor or trace element which partitions readily into the melt phase rather than crystalline phases.
Area between the other major mineral phases.
a line on a diagram passing through plots of samples with the same age but differing isotope ratios.
atoms of a specific element which differ in number of neutrons in the nucleus; this results in different atomic weights, and slightly differing chemical properties.
iron meteorite
a class of meteorite composed mainly of iron or iron-nickel metal.
an MgO-rich rock thought to have formed by large percentages (20-30%) of melting of the Earth's mantle. Found mainly in the Archean period of Earth history.
Japanese Antarctic Research Expedition
Lyndon B. Johnson Space Center, Houston, Texas 77058
katabatic wind
The wind that blows off of the Antarctic continent.
An acronym for a lunar crustal component rich in potassium (K), the rare earth elements (REE), phosphorus (P), and other incompatible elements.
Lagrangian points
the five equilibrium points in the restricted three-body problem. Two of the Lagrange points (L4 and L5) are located at the vertices of equilateral triangles formed by the two primaries (e.g., Sun and Saturn, or Saturn and satellite) and are stable; the other three are unstable and lie on the line connecting the two primaries.
late veneer
in heterogeneous accretion theory, the late addition of material to a planet after a metallic core has formed.
the line or surface in a phase diagram above which the system is completely liquid.
lithophile element
an element tending to concentrate in oxygen-containing compounds (silicates) as opposed to metal or sulfide.
an outer shell of a planet which has high rock strength and undergoes brittle deformation.
Two pyroxene rock, plutonic.
Low Ti basalt
class of lunar basalts with low Ti content, compared to high Ti lunar basalts (but still high compared to terrestrial basalt)
Soviet unmanned missions to the Moon that returned samples robotically
lunar capture theory
the hypothesis that the Moon was gravitationally captured by the Earth.
lunar cataclysm
the hypothesis that the Moon underwent a heavy bombardment period at approximately 3.9 Ga.
lunar fission theory
the hypothesis that the Moon was formed by separation or fission from the Earth.
lunar co-accretion theory
the hypothesis that the Moon and Earth accreted together.
Lunar Prospector
mission to Moon that included GRS instrument for elemental mapping
1,000,000 years
magnesian suite rocks of the Moon
Meteorite Working Group. U. S. advisory panel to NSF/NASA/Smithsonian.
magma ocean
a globally extensive layer of magma on a planet or moon which consists of >50% melt.
magmatic inclusion
small recrystallized glass inclusions usually found in early-formed olivine or chromite crystals (presumably trapped magmatic liquid)
magnesian perovskite
a mineral with the formula MgSiO3 which is stable at high pressures (>250 kb as exist deep with the Earth's mantle).
an oxide with the formula (Mg,Fe)O; likely to be stable in Earth's lower mantle.
a component of garnet that is stable at high pressures and temperature in which no aluminum is present - only silica. It has the general formula of (Mg,Fe)4Si4O12.
the zone of a planet beneath its crust and above its core.
mare basalt
basalts that form the lunar maria, which are the dark colored areas on the Moon.
Regions on the Moon of excess mass concentrations per unit area identified by positive gravity anomalies and associated with mare-filled multi-ring basins.
Shock event that converts plagioclase into isotropic phase.
stony-iron meteorites that consist of a brecciated mixture of iron-nickel metal and silicate minerals and pieces of gabbro and basalt.
Fine-grained mineral mass found interstitial to major minerals.
mineralogical mode
the mineral percentages, usually expressed as volume percent
" mineral" separate
An attempt to obtain a concentration of one mineral phase after powdering the rock and using various mechanical means (e.g. heavy liquids for density difference).
moment of inertia
a quantity related to the density distribution within a planet, specifically, the tendency for an increase of density with depth.
Northeast Africa
National Institute of Polar Research, Tokyo, Japan
noble gases
the rare gases helium, neon, argon, krypton, xenon and radon.
noble metals
Gold (Au), rhenium(Re) and the platinum group elements, platinum (Pt), rhodium (Rh), ruthenium (Ru), iridium (Ir), osmium (Os) and palladium (Pd).
a rock type (found among Apollo samples) consisting of orthopyroxene and feldspar
atoms characterized by the number of protons (Z) and neutrons (N). The mass number (A) = Z + N; isotopes are nuclides with the same number of protons, but differing numbers of neutrons; isobars have the same mass number (A) but different numbers of protons (Z) and neutrons (N).
North West Africa. Meteorites usually purchased from nomads in Morocco, but probably found in Algeria or even further east in Sahara.
a common silicate mineral within Earth's upper mantle and chondritic meteorites, with the general formula of (Mg,Fe)2SiO4.
Texture of basaltic rock where pyroxene completely encloses plagioclase and other phases.
orbital resonances
orbital locations where pairs of orbital frequencies are in ratios of small whole numbers.
large basin on the far side of the Moon
an orthorhombic member of the pyroxene mineral group, with the general formula of (Mg,Fe)2Si2O6.
stony-iron meteorites comprised of roughly equal amounts of olivine and iron nickel metal. They are thought to be pieces of the core-mantle boundary of a small differentiated planetesimal.
partition coefficient
the ratio of the concentration of a trace element in one phase to its concentration in a second phase with which it is in equilibrium. Phases can be solid or liquid, metals or silicates.
the process by which a liquid settles through a solid matrix.
the mineral MgO.
an igneous rock comprised of mainly pyroxene and olivine
high MgO, and usually olivine-bearing, basaltic rocks thought to be derived by melting of peridotite.
the calcium and sodium-bearing mineral series within the feldspar group.
bodies from millimeter to about a kilometer in size that are believed to have formed during the early planet-forming process.
plateau age
The age obtained from the 39Ar/40Ar spectrum as function of release temperature.
a term applied to igneous rocks which have crystallized at depth, usually with coarsely crystalline texture.
Texture of igneous rock where small granular crystals are irregularly scattered without common orientation in a larger crystal of another mineral.
the volume percentage of a rock (or other material) that is occupied by voids or fluid.
parts per billion (by weight)
parts per million (by weight)
parts per trillion (by weight)
a slow, periodic conical motion of the rotation axis of a spinning body.
The history of the sample before entry into the Earth's atmosphere - as judged by location with respect to fusion crust.
primitive upper mantle
estimated composition of Earth's mantle after core formation, and before continental crust formation.
large basin on the Moon
Procellarum KREEP Terrane (PKT)
large KREEP-rich terrane on the near side of the Moon
a term referring to an isotope having been formed from a radioactive parent.
rare earth element (REE)
a collective term for the elements with atomic number 57- 71, or the lanthanide series.
rare gases
see the noble gases
refractory element
an element that vaporizes at high very high temperatures, such as U, Al, Ca and the REE.
selective response of any periodic system to an external stimulus of the same frequency as the natural frequency of the system.
radiochemical neutron activation analysis (generally superior to INAA, because of use of internal standard
Roche Limit
the critical separation between two bodies with no tensile strength at which tidal forces are so strong that the smaller body is torn apart; for the Earth and Moon, this distance is about 2.9 Earth radii.
Sayh al Uhaymir, Oman
SELenological and ENgineering Explorer; A Japanese robotic mission to the Moon scheduled for launch in August 2007.
Scanning electron microscope
semimajor axis
half the length of the major axis of an orbit (its greatest diameter).
short-lived radionuclide
see extinct nuclide
siderophile element
an element which preferentially enters the metal phase (" sidero" = iron, and " phile" = loving).
a mineral or compound whose crystal structure contains SiO4 tetrahedra.
Secondary Ion Mass Spectroscopy
Robotic mission to the Moon funded by the European Space Agency (ESA); Small Missions for Advanced Research in Technology
see USNM below
solar nebula
the primitive disk-shaped cloud of dust and gas from which all bodies in the solar system originated.
the line or surface on a phase diagram below which the system is completely solid.
SPA (South Pole - Aitken basin)
largest lunar basin and located in the south polar region
smoothed particle hydrodynamics.
a group of oxide minerals with similar physical and chemical properties and with the general formula of AB2O4.
transmission electron microscope
terrestrial age
Time interval that meteorite has spent on Earth (for example, can sometimes be determined by determination of carbon 14)
trace element
an element found in very low (trace) amounts - 100 ppm or less.
rock type (found among Apollo samples) consisting of olivine and plagioclase feldspar
fresh young crater on the southern part of the near side of the Moon
United States National Museum, also called the Smithsonian Institution, Washington D.C. Specifically, the Department of Mineral Sciences is a great source of research samples.
the resistance that a fluid system offers to flow when it is subjected to a shear stress. It is a measure of the internal friction that results when velocity gradients exist within a system.
VLT (very low titanium basalt)
class of lunar basalts with very low Ti content, compared to other lunar basalts (but still high compared to terrestrial basalt)
volatile element
an element with a low vaporization temperature such as the alkalis (K, Na) or Pb.
Term used for a small sample (50 mg-2 g) of a rock used to determine the chemical composition of the "whole" specimen. Generally selected to be representative of the "whole" , but, obviously, NOT the whole rock.
X-ray diffraction
X-ray fluorescence
Young's modulus
the proportionality constant between stress (force per unit area) and strain (change in length per unit length) for an elastic material. In cgs units it is expressed in dynes per cm2 or lbs per ft2 (PSI).